高碘酸钾氧化变色酸2R褪色光度法测定痕量锡Ⅳ

Catalytic spectrophotometric determination of trace tinⅣ based on discoloring of chromotrope 2R oxidized by potassium periodate

基于在稀H2SO4介质中,痕量锡(Ⅳ)催化高碘酸钾氧化变色酸2R(CMT2R)的褪色反应,建立了测定痕量锡(Ⅳ)的催化动力学光度法.方法检出限为0.24μg/L,线性范围为0.0～8.0μg/L.在25 mL溶液中,测定0.2μg锡(Ⅳ)的相对标准偏差为3.4%(n=11).讨论了酸度、反应物浓度、温度、反应时间、干扰离子等因素的影响;研究了反应的最佳条件,并测定了一些动力学参数,催化反应的表观活化能为54.42kJ/mol.结合巯基葡聚糖凝胶(SDG)分离富集,实现了样品中痕量锡(Ⅳ)的测定.方法经水系沉积物国家标准物质分析验证,结果与认定值相符;用于测定环境水样、人发样品中痕量锡(Ⅳ),相对标准偏差为3.4%～4.2%,标准加入回收率为98.5%～104.0%.

Based on the catalytic effect of trace tin（Ⅳ） on discoloring reaction of chromotrope 2R with potassium periodate in dilute sulphuric acid solution, a method for the determination of trace tin（Ⅳ） by kinetic spectrophotometry has been developed. The detection limit is 0.24μg/L and the linear range of determination is 0.0 - 8.0μg/L for tin（Ⅳ）. The relative standard deviation for the determination of tin（Ⅳ） at the concentration of 0.2 μg/25mL is 3.4 % （n = 11）. The factors such as acidity, concentrations of reactant, reaction time, temperature, influence of coexisting ions on the reaction and the optimum reaction conditions of reaction and some kinetic parameters are discussed. The apparent activation energy of the reaction is 54.42 kJ/mol. Combined with mercapto containing dextran gel separation and enrichment, the method has been verified by analysis of national certified reference materials （stream sediment samples）, the results are in agreement with certified values. The method has also been applied to the determination of trace tin（Ⅳ） in environmental water and human hair samples with the relative standard deviation of 3.4 % - 4.2 % and the recovery of 98.5% - 104.0%.